Oligomer-polymer and lithium battery

ABSTRACT

A lithium battery including an anode, a cathode, an isolation film, an electrolyte solution, and a package structure is also provided, wherein the cathode includes the oligomer-polymer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 15/619,061, filed on Jun. 9, 2017, now pending, which claimsthe priority benefit of Taiwan application serial no. 105136149, filedon Nov. 7, 2016. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an oligomer-polymer, and more particularly, toan oligomer-polymer for a lithium battery.

Description of Related Art

Since primary batteries are not environment-friendly, the market demandfor secondary lithium batteries with characteristics such asrechargeability, light weight, high voltage value, and high energydensity has been growing in recent years. As a result, the currentperformance requirements for secondary lithium batteries such as lightweight, durability, high voltage, high energy density, and high safetyhave become higher. In particular, secondary lithium batteries have veryhigh potential in the application and expandability in light electricvehicles, electric vehicles, and the large power storage industry.

However, among the commercialized secondary lithium batteries in thegeneral market, since lithium transition metal oxide is used as thecathode, the cathode readily reacts with the electrolyte solution inhigh temperature applications and becomes damaged. As a result, oxygenin the lithium metal oxide is released and becomes part of a combustionreaction. This is one of the main causes for the explosion, swelling,and performance degradation of the secondary lithium battery. Therefore,continuously maintaining good structural stability of the cathodematerial in high temperature applications is one of the desired goals ofthose skilled in the art.

SUMMARY OF THE INVENTION

The invention provides an oligomer-polymer that can be applied in thecathode material of a lithium battery such that the lithium batterystill has good performance in a high-temperature environment.

The oligomer-polymer of the invention is obtained by the polymerizationreaction of a compound containing an ethylenically unsaturated group anda nucleophile compound, wherein the nucleophile compound includes acompound shown in formula 1 below:

In an embodiment of the invention, the mole ratio of the compoundcontaining an ethylenically unsaturated group and the nucleophilecompound is between 2:1 and 1:1.

In an embodiment of the invention, the compound containing anethylenically unsaturated group includes a maleimide-based compound.

In an embodiment of the invention, the maleimide-based compoundincludes, for instance, monomaleimide or bismaleimide.

In an embodiment of the invention, the nucleophile compound furtherincludes the compound shown in formula 2 below:

In an embodiment of the invention, in the nucleophile compound, the moleratio of the compound shown in formula 1 and the compound shown informula 2 is between 2:1 and 1:1.

In an embodiment of the invention, the reaction temperature of thepolymerization reaction is between 25° C. and 200° C.

A lithium battery of the invention includes an anode, a cathode, anisolation film, an electrolyte solution, and a package structure. Thecathode and the anode are separately disposed, and the cathode includesany of the above oligomer-polymers. The isolation film is disposedbetween the anode and the cathode, and the isolation film, the anode,and the cathode define a housing region. The electrolyte solution isdisposed in the housing region. The package structure packages theanode, the cathode, and the electrolyte solution.

In an embodiment of the invention, the electrolyte solution includes anorganic solvent, a lithium salt, and an additive.

In an embodiment of the invention, the additive includes monomaleimide,polymaleimide, bismaleimide, polybismaleimide, a copolymer ofbismaleimide and monomaleimide, vinylene carbonate, or a mixturethereof.

Based on the above, by using the compound containing an ethylenicallyunsaturated group and the nucleophile compound including the compoundshown in formula 1 to prepare the oligomer-polymer of the invention, theoligomer-polymer of the invention can be applied in the cathode materialof a lithium battery, such that the lithium battery still has goodcapacitance, battery efficiency, and charge and discharge cycle lifeeven in high-temperature operation.

In order to make the aforementioned features and advantages of thedisclosure more comprehensible, embodiments accompanied with figures aredescribed in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a cross-sectional schematic of a lithium battery according toan embodiment of the invention.

FIG. 2 shows a curve diagram illustrating the relationship betweencapacitance and voltage of the lithium battery of each of Example 1 andComparative Examples 1 and 2 of the invention at room temperature.

FIG. 3 shows a diagram illustrating the relationship between the numberof charge and discharge cycles and discharge capacity of the lithiumbattery of each of Example 1 and Comparative Example 2 of the inventionat room temperature.

FIG. 4 shows a diagram illustrating the relationship between the numberof charge and discharge cycles and discharge capacity of the lithiumbattery of each of Example 1, Comparative Example 1, and ComparativeExample 2 of the invention at high temperature.

DESCRIPTION OF THE EMBODIMENTS

In the present specification, a range represented by “a numerical valueto another numerical value” is a schematic representation for avoidinglisting all of the numerical values in the range in the specification.Therefore, the recitation of a specific numerical range covers anynumerical value in the numerical range and a smaller numerical rangedefined by any numerical value in the numerical range, as is the casewith any numerical value and the smaller numerical range in thespecification.

Moreover, in the present specification, skeleton formulas are sometimesused to represent compound structures. Such representation can omitcarbon atoms, hydrogen atoms, and carbon-hydrogen bonds. Of course,structural formulas with clear illustrations of functional groups aredefinitive.

To prepare an oligomer-polymer that can be applied in the cathodematerial of a lithium battery such that the lithium battery still hasgood performance in a high-temperature environment, the inventionprovides an oligomer-polymer that can achieve the advantages above. Inthe following, embodiments are provided as examples of actualimplementation of the invention.

An embodiment of the invention provides an oligomer-polymer. Theoligomer-polymer is obtained by the polymerization reaction of acompound containing an ethylenically unsaturated group and a nucleophilecompound, wherein the nucleophile compound includes the compound shownin formula 1:

In the present embodiment, the compound containing an ethylenicallyunsaturated group includes, for instance, a maleimide-based compound.Specifically, in the present embodiment, the maleimide-based compoundincludes, for instance, monomaleimide or bismaleimide. The monomaleimideis, for instance, selected from the group consisting of unsubstitutedmaleimide, N-phenylmaleimide, N-(o-methylphenyl)-maleimide,N-(m-methylphenyl)-maleimide, N-(p-methylphenyl)-maleimide,N-cyclohexylmaleimide, maleimidophenol, maleimidobenzocyclobutene,phosphorus-containing maleimide, phosphonate-containing maleimide,siloxane-containing maleimide,N-(4-tetrahydropyranyl-oxyphenyl)maleimide, and 2,6-xylylmaleimide; andthe bismaleimide can have the structure represented by formula I:

wherein R₁ includes:—(CH₂)₂—, —(CH₂)₆—, —(CH₂)₈—, —(CH₂)₁₂—,

Moreover, in the present embodiment, the oligomer-polymer is obtained bythe addition polymerization reaction of the compound containing anethylenically unsaturated group and the nucleophile compound via aMichael addition reaction. In other words, at this point, the Michaeladdition reaction occurs between oxygen atoms of the hydroxyl group inthe compound shown in formula 1 and C—C double bonds in the compoundcontaining an ethylenically unsaturated group. Specifically, theaddition polymerization reaction of the compound containing anethylenically unsaturated group and the nucleophile compound can beperformed using any known method.

In an embodiment, a method of performing the addition polymerizationreaction on the compound containing an ethylenically unsaturated groupand the nucleophile compound includes, for instance: dissolving thecompound containing an ethylenically unsaturated group and thenucleophile compound in a solvent and reacting the mixture at atemperature of 25° C. to 200° C. for 0.5 hours to 5 hours.

In the above steps, the mole ratio of the compound containing anethylenically unsaturated group and the nucleophile compound is between2:1 and 1:1. If the mole ratio of the compound containing anethylenically unsaturated group and the nucleophile compound is lessthan 2:1, then the Michael addition reactivity is poor; and if the moleratio of the compound containing an ethylenically unsaturated group andthe nucleophile compound is higher than 1:1, then an excessive amount ofthe nucleophile compound remains such that an electrochemical sidereaction occurs.

The solvent can be an organic solvent, such as (but not limitedto)N-methyl pyrollidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethylacetamide (DMAC), or a combination thereof.

In another embodiment, the addition polymerization reaction can also beperformed in the presence of a catalyst, i.e., the compound containingan ethylenically unsaturated group, the nucleophile compound, and thecatalyst are dissolved in the solvent for the reaction. At this point,the reaction temperature is, for instance, between, 25° C. and 80° C.,the reaction time is, for instance, between 0.5 hours and 2 hours, thecatalyst is, for instance, triethylamine or dibenzyl trithiocarbonate(DBTTC), and the content of the catalyst is, for instance, 1 part byweight to 10 parts by weight.

Moreover, in the present embodiment, the nucleophile compound canfurther include the compound shown in formula 2 below:

Specifically, the compound shown in formula 1 and the compound shown informula 2 are tautomers, and the compound shown in formula 2 tends to beconverted into the compound shown in formula 1 when the pH is greaterthan 6. As a result, as described above, when the oligomer-polymer isprepared by a Michael addition reaction under alkaline conditions, thenucleophile compound must include the compound shown in formula 1.

More specifically, since the pH of the reaction environment affects thebalance between the compound shown in formula 1 and the compound shownin formula 2, the ratio of the compound shown in formula 1 and thecompound shown in formula 2 in the nucleophile compound changes with thepH. For instance, in comparison to weak alkaline reaction conditions,under strong alkaline reaction conditions, the proportion of thecompound shown in formula 1 in the nucleophile compound is higher, eventhe compound shown in formula 2 may not even exist. In other words, inthe present embodiment, the oligomer-polymer can be obtained by thepolymerization reaction of the compound containing an ethylenicallyunsaturated group and the compound shown in formula 1, or theoligomer-polymer can be obtained by the polymerization reaction of thecompound containing an ethylenically unsaturated group, the compoundshown in formula 1, and the compound shown in formula 2, and the ratioof the compound shown in formula 1 and the compound shown in formula 2changes with the pH.

In an embodiment, the oligomer-polymer is prepared under the followingconditions: the compound containing an ethylenically unsaturated group,the nucleophile compound, and the triethylamine catalyst are dissolvedin an N-methylpyrrolidone solvent, and the mixture is reacted at atemperature of 30° C. to 50° C. for 0.5 hours to 2 hours. At this point,since N-methylpyrrolidone is weakly alkaline and triethylamine is a weakalkaline catalyst, the nucleophile compound includes the compound shownin formula 1 and the compound shown in formula 2, and the synthesis moleratio is between 2:1 and 1:1. From another perspective, a Michaeladdition reaction is performed on oxygen atoms of the hydroxyl group inthe compound shown in formula 1 and nitrogen atoms of secondary amine inthe compound shown in formula 2 with C—C double bonds in the compoundcontaining an ethylenically unsaturated group.

It should be mentioned that, in the present embodiment, theoligomer-polymer has a hyperbranched structure. “Hyperbranchedstructure” is a structure formed by adding the nucleophile compound onthe C—C double bonds of the compound containing an ethylenicallyunsaturated group such that the C—C double bonds of the compoundcontaining an ethylenically unsaturated group can be opened up allowingthe two carbon atoms or one of the two carbon atoms to bond with otheratoms for branching and ordering polymerization reactions by using thecompound containing an ethylenically unsaturated group as anarchitecture matrix during the addition polymerization reaction of thecompound containing an ethylenically unsaturated group and thenucleophile compound (i.e., the compound shown in formula 1, or thecompound shown in formula 1 and the compound shown in formula 2).

It should be mentioned that, the oligomer-polymer obtained by thepolymerization reaction of the compound containing an ethylenicallyunsaturated group and the nucleophile compound (i.e., the compound shownin formula 1, or the compound shown in formula 1 and the compound shownin formula 2) can be applied in the cathode material of a lithiumbattery. More specifically, the oligomer-polymer forms a protectivelayer on the surface of the cathode material, and the protective layercan effectively prevent damage to the cathode structure in ahigh-temperature environment, with the reason being that theoligomer-polymer has a hyperbranched structure as described above, andtherefore the oligomer-polymer can form a stable complex with the metaloxide in a regular cathode material and be distributed on the surfacethereof. Moreover, since the oligomer-polymer has a rigid chemicalstructure, the resulting protective layer can have high thermalstability. In this way, the lithium battery having the cathode materialincluding the oligomer-polymer can still have good capacitance, batteryefficiency and safety in a high-temperature environment, and the cyclelife of the battery can be improved.

Another embodiment of the invention provides a lithium battery includingthe oligomer-polymer in any one of the above embodiments. In thefollowing, description is provided with reference to FIG. 1.

FIG. 1 is a cross-sectional schematic of a lithium battery according toan embodiment of the invention.

Referring to FIG. 1, a lithium battery 100 includes an anode 102, acathode 104, an isolation film 106, an electrolyte solution 108, and apackage structure 112.

In the present embodiment, the anode 102 includes an anode metal foil102 a and an anode material 102 b, wherein the anode material 102 b isdisposed on the anode metal foil 102 a through coating or sputtering.The anode metal foil 102 a is, for instance, a copper foil, an aluminumfoil, a nickel foil, or a high-conductivity stainless steel foil. Theanode material 102 b is, for instance, carbide or metal lithium. Thecarbide used as the anode material 102 b is, for instance, carbonpowder, graphite, carbon fiber, carbon nanotube, graphene, or a mixturethereof. However, in other embodiments, the anode 102 can also onlyinclude the anode material 102 b.

The cathode 104 and the anode 102 are separately disposed. The cathode104 includes a cathode metal foil 104 a and a cathode material 104 b,wherein the cathode material 104 b is disposed on the cathode metal foil104 a through coating. The cathode metal foil 104 a is, for instance, acopper foil, an aluminum foil, a nickel foil, or a high-conductivitystainless steel foil. The cathode material 104 b includes theoligomer-polymer in any one of the above embodiments and a lithium-mixedtransition metal oxide. Specifically, in the present embodiment, theoligomer-polymer is used as a cathode material additive. Thelithium-mixed transition metal oxide is, for instance,LiAl_(0.05)Co_(0.95)O, LiMnO₂, LiMn₂O₄, LiCoO₂, Li₂Cr₂O₇, Li₂CrO₄,LiNiO₂, LiFeO₂, LiNi_(x)Co_(1-x)O₂, Li[NiLi_((1-2x)/3)Mn_((2-x)/3)]O₂,LiFePO₄, LiMn_(0.5)Ni_(0.5)O₂, LiMn_(1/3)Co_(1/3)Ni_(1/3)O₂,LiMc_(0.5)Mn_(1.5)O₄, or a combination thereof, where 0<x<1 and Mc is adivalent metal. Moreover, in the present embodiment, based on a totalweight of 100 parts by weight of the cathode material 104 b, the contentof the oligomer-polymer is 0.1 parts by weight to 10 parts by weight,preferably 0.1 parts by weight to 5 parts by weight; and the content ofthe lithium-mixed transition metal oxide is, for instance, 80 parts byweight to 92 parts by weight, preferably 85 parts by weight to 90 partsby weight. If the content of the oligomer-polymer is less than 0.1 partsby weight, then the battery safety characteristic is not significant;and if the content of the oligomer-polymer is higher than 10 parts byweight, then the battery cycle life is poor.

Moreover, in an embodiment, the lithium battery 100 can further includea polymer binder, and the polymer binder reacts with the anode 102and/or the cathode 104 to increase the mechanical properties of theelectrode(s). Specifically, the anode material 102 b can be adhered tothe anode metal foil 102 a through the polymer binder, and the cathodematerial 104 b can be adhered to the cathode metal foil 104 a throughthe polymer binder. The polymer binder is, for instance, polyvinylidenedifluoride (PVDF), styrene-butadiene rubber (SBR), polyamide, melamineresin, or a combination thereof.

The isolation film 106 is disposed between the anode 102 and the cathode104, and the isolation film 106, the anode 102, and the cathode 104define a housing region 110. The material of the isolation film 106 is,for instance, an insulating material, and the insulating material can bepolyethylene (PE), polypropylene (PP), or a multilayer compositestructure of the materials, such as PE/PP/PE.

In the present embodiment, the electrolyte solution 108 is disposed inthe housing region 110, and the electrolyte solution 108 includes anorganic solvent, a lithium salt, and an additive. In particular, thecontent of the organic solvent in the electrolyte solution 108 is 55 wt% to 90 wt %, the content of the lithium salt in the electrolytesolution 108 is 10 wt % to 35 wt %, and the content of the additive inthe electrolyte solution 108 is 0.05 wt % to 10 wt %. However, in otherembodiments, the electrolyte solution 108 may also not include anadditive.

The organic solvent is, for instance, γ-butyrolactone (GBL), ethylenecarbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC),propyl acetate (PA), dimethyl carbonate (DMC), ethylmethyl carbonate(EMC), or a combination thereof.

The lithium salt is, for instance, LiPF₆, LiBF₄, LiAsF₆, LiSbF₆, LiClO₄,LiAlCl₄, LiGaCl₄, LiNO₃, LiC(SO₂CF₃)₃, LiN(SO₂CF₃)₂, LiSCN, LiO₃SCF₂CF₃,LiC₆F₅SO₃, LiO₂CCF₃, LiSO₃F, LiB(C₆H₅)₄, LiCF₃SO₃, or a combinationthereof.

The additive includes, for instance, monomaleimide, polymaleimide,bismaleimide, polybismaleimide, a copolymer of bismaleimide andmonomaleimide, vinylene carbonate (VC), or a mixture thereof. Themonomaleimide is, for instance, selected from the group consisting ofunsubstituted maleimide, N-phenylmaleimide,N-(o-methylphenyl)-maleimide, N-(m-methylphenyl)-maleimide,N-(p-methylphenyl)-maleimide, N-cyclohexylmaleimide, maleimidophenol,maleimidobenzocyclobutene, phosphorus-containing maleimide,phosphonate-containing maleimide, siloxane-containing maleimide,N-(4-tetrahydropyranyl-oxyphenyl)maleimide, and 2,6-xylylmaleimide. Thebismaleimide can have the structure represented by formula I above.

The package structure 112 is used to package the anode 102, the cathode104, and the electrolyte solution 108. The material of the packagestructure 112 is, for instance, aluminum foil.

It should be mentioned that, the cathode material 104 b of the lithiumbattery 100 includes the oligomer-polymer and the lithium-mixedtransition metal oxide, and therefore, as described above, theoligomer-polymer having a hyperbranched structure can form a stablecomplex with the lithium-mixed transition metal oxide and form theprotective layer on the surface of the lithium-mixed transition metaloxide. Moreover, since the oligomer-polymer has the rigid chemicalstructure, the resulting protective layer can have high thermalstability. In this way, the lithium battery 100 having the cathodematerial 104 b including the oligomer-polymer can still have goodcapacitance, safety, and battery efficiency in a high-temperatureenvironment, and the cycle life of the battery can be improved.

Moreover, the cathode 104 having the protective layer in the lithiumbattery 100 can be formed by adding the oligomer-polymer in the cathodematerial in a current battery manufacturing process. Therefore, thecapacitance, battery efficiency, and charge and discharge cycle life ofthe lithium battery 100 can be effectively maintained at hightemperature without modifying any battery design, electrode material andelectrolyte solution.

Example 1 and Comparative Examples 1 to 2 are provided below to morespecifically describe the invention. Although the following examples aredescribed, the materials used and the amount and ratio thereof, as wellas handling details and handling process . . . etc., can be suitablymodified without exceeding the scope of the invention. Accordingly,restrictive interpretation should not be made to the invention based onthe experiments described below.

Example 1 Preparation of Anode

Metal lithium was cut into a suitable shape and inserted directly toform the anode.

Preparation of Cathode

40 parts by weight (0.5 moles) of a compound containing an ethylenicallyunsaturated group, 50 parts by weight (0.5 moles) of a nucleophilecompound, and 10 parts by weight of a triethylamine catalyst were addedin a suitable amount of an N-methylpyrrolidone solvent, and thecomponents were mixed and stirred to react for 2 hours at a temperatureof 25° C. to prepare the oligomer-polymer of Example 1, wherein thestructural formula of the compound containing an ethylenicallyunsaturated group is as shown in formula I:

formula I, R₁ in formula I is

and a suitable synthesis mole ratio of the compound shown in formula 1and the compound shown in formula 2 in the nucleophile compound is about3:2.

Next, 90 parts by weight of LiAl_(0.05)Co_(0.95)O₂, 5 parts by weight ofpolyvinyl difluoride (PVDF), and 5 parts by weight of acetylene black(conductive powder) were uniformly mixed in the N-methylpyrrolidonesolvent. Next, 0.5 parts by weight of the oligomer-polymer of Example 1was added to the mixed solution to form the cathode material. Then,after the material was coated on an aluminum foil, the aluminum foilwith the material coated thereon was dried, compressed, and then cut toform the cathode.

Preparation of Electrolyte Solution

LiPF₆ was dissolved in a mixed solution of propylene carbonate (PC),ethylene carbonate (EC), and diethyl carbonate (DEC) (volume ratio:PC/EC/DEC=2/3/5) to prepare an electrolyte solution having aconcentration of 1 M, wherein the mixed solution was used as an organicsolvent in the electrolyte solution, and LiPF₆ was used as lithium saltin the electrolyte solution.

Manufacture of Lithium Battery

After polypropylene was used as the isolation film to isolate the anodeand the cathode and define the housing region, the electrolyte solutionwas added in the housing region between the anode and the cathode.Lastly, the above structure was sealed with a package structure tocomplete the manufacture of the lithium battery of Example 1.

Comparative Example 1 Preparation of Anode

The anode of Comparative Example 1 was prepared based on the samepreparation process as Example 1.

Preparation of Cathode

40 parts by weight (0.5 moles) of a maleimide-based compound, 50 partsby weight (0.5 moles) of a barbituric acid compound, and 10 parts byweight of a triethylamine catalyst were added in a suitable amount of anN-methylpyrrolidone solvent, and the components were mixed and stirredto react for 3 hours at a temperature of 80° C. to prepare theoligomer-polymer of Comparative Example 1, wherein the structuralformula of the maleimide-based compound is as shown in formula I:

R₁ in formula I is

the structural formula of the barbituric acid compound is as shown informula II below, and R₂ and R₃ in formula II are H:

Next, 90 parts by weight of LiAl_(0.05)Co_(0.95)O₂, 5 parts by weight ofpolyvinyl difluoride (PVDF), and 5 parts by weight of acetylene black(conductive powder) were uniformly mixed in the N-methylpyrrolidonesolvent. Next, 0.5 parts by weight of the oligomer-polymer ofComparative Example 1 was added in the mixed solution to form thecathode material. Then, after the material was coated on an aluminumfoil, the aluminum foil with the material coated thereon was dried,compressed, and then cut to form the cathode.

Preparation of Electrolyte Solution

The electrolyte solution of Comparative Example 1 was prepared based onthe same preparation process as Example 1.

Manufacture of Lithium Battery

The lithium battery of Comparative Example 1 was made according to asimilar manufacturing process as Example 1, and the difference thereofis only in that: in the lithium battery of Comparative Example 1, thecathode material includes the oligomer-polymer of Comparative Example 1;and in the lithium battery of Example 1, the cathode material includesthe oligomer-polymer of Example 1.

Comparative Example 2 Preparation of Anode

The anode of Comparative Example 2 was prepared based on the samepreparation process as Example 1.

Preparation of Cathode

The cathode of Comparative Example 2 was prepared according to a similarpreparation process as Example 1, and the difference thereof is only inthat: no cathode material additive was added in the cathode material ofComparative Example 2.

Preparation of Electrolyte Solution

The electrolyte solution of Comparative Example 2 was prepared based onthe same preparation process as Example 1.

Manufacture of Lithium Battery

The lithium battery of Comparative Example 2 was made according to asimilar manufacturing process as Example 1, and the difference thereofis only in that: in the lithium battery of Comparative Example 2, nocathode material additive was added in the cathode material; and in thelithium battery of Example 1, the cathode material includes theoligomer-polymer of Example 1.

Next, a charge and discharge performance test was performed on thelithium batteries of Example 1 and Comparative Examples 1 to 2, and themeasurement results thereof are shown in Table 1 and FIG. 2. A chargeand discharge cycle test was performed on the lithium batteries ofExample 1 and Comparative Example 2, and the measurement results thereofare shown in Table 2 and FIG. 3.

Charge and Discharge Performance Test

The first cycle of charge and discharge was performed on the lithiumbatteries of Example 1 and Comparative Examples 1 to 2 at fixedcurrent/voltage at room temperature (30° C.) using a potentiostat (madeby Biologic Corporation, model: VMP3). First, the batteries were chargedto 4.8 V with a constant current of 0.1 C until the current was lessthan or equal to 0.02 C. Then, the batteries were discharged to thecut-off voltage 2 V with a constant current of 0.1 C. The dischargecapacity and irreversibility ratio of the lithium batteries of Example 1and Comparative Examples 1 to 2 are recorded in Table 1 below. FIG. 2shows a curve diagram illustrating the relationship between capacitanceand voltage of the lithium battery of each of Example 1 and ComparativeExamples 1 and 2 of the invention at room temperature.

TABLE 1 Discharge capacity Irreversibility ratio (mAh/g) (%) Example 1225.1 86.4 Comparative 220.8 83.5 Example 1 Comparative 219.5 84.5Example 2

It can be known from Table 1 and FIG. 2 that, in comparison to thelithium batteries of Comparative Examples 1 to 2, the lithium battery ofExample 1 has higher discharge capacity and a similar irreversibilityratio. The results indicate that by preparing the cathode using theoligomer-polymer of the invention obtained by the polymerizationreaction of the compound containing an ethylenically unsaturated groupand the nucleophile compound including the compound shown in formula 1,not only are battery characteristics not affected, overall energydensity of the battery is also increased.

Charge and Discharge Cycle Test

The lithium battery of each of Example 1 and Comparative Example 2 wascharged and discharged at fixed current/voltage at room temperature (30°C.) using a potentiostat (made by Biologic Corporation, model: VMP3).First, the charge and discharge cycle was repeated 20 times according tothe following conditions: the battery was charged to 4.8 V at a fixedcurrent of 0.1 C until the current was less than or equal to 0.02 C, andthen the battery was discharged to the cutoff voltage (3 V) at a fixedcurrent of 0.1 C. After the 20 charge and discharge cycles wereperformed, the charge and discharge cycle was repeated 10 timesaccording to the following conditions: the battery was charged to 4.8 Vat a fixed current of 0.1 C until the current was less than or equal to0.02 C, and then the battery was discharged to the cutoff voltage (3 V)at a fixed current of 0.2 C. Lastly, the charge and discharge cycle wasrepeated again 10 times according to the following conditions: thebattery was charged to 4.8 V at a fixed current of 0.1 C until thecurrent was less than or equal to 0.02 C, and then the battery wasdischarged to the cutoff voltage (3 V) at a fixed current of 0.5 C tocomplete a total of 40 charge and discharge cycles. The dischargecapacity of the lithium battery of each of Example 1 and ComparativeExample 2 of the 40th cycle and the retention rate of the dischargecapacity after 40 charge and discharge cycles are recorded in Table 2below. FIG. 3 shows a diagram illustrating the relationship between thenumber of charge and discharge cycles and discharge capacity of thelithium battery of each of Example 1 and Comparative Example 2 of theinvention at room temperature.

TABLE 2 Discharge capacity of 40th cycle Retention rate (mAh/g) (%)Example 1 144.6 74.9 Comparative 132.0 81.8 Example 2

It can be known from Table 2 and FIG. 3 that, in comparison to thelithium battery of Comparative Example 2, after 40 charge and dischargecycles at room temperature, the lithium battery of Example 1 has higherdischarge capacity and capacitance retention rate. The results indicatethat by preparing the cathode using the oligomer-polymer of theinvention obtained by the polymerization reaction of the compoundcontaining an ethylenically unsaturated group and the nucleophilecompound including the compound shown in formula 1, the cathode canstill have good structural stability after 40 charge and dischargecycles at room temperature, such that the lithium battery can have goodcapacitance, battery efficiency, and charge and discharge cycle life.Moreover, the results also prove that the oligomer-polymer of theinvention can indeed be accepted by the current lithium battery andimprove the safety of the battery.

Moreover, the lithium battery of each of Example 1, Comparative Example1, and Comparative Example 2 was charged and discharged at fixedcurrent/voltage at high temperature (55° C.) using a potentiostat (madeby Biologic Corporation, model: VMP3). The charge and discharge cyclewas repeated 10 times according to the following conditions: the batterywas charged to 4.8 V at a fixed current of 0.1 C until the current wasless than or equal to 0.02 C, and then the battery was discharged to thecutoff voltage (3 V) at a fixed current of 0.1 C. The discharge capacityof the lithium battery of each of Example 1, Comparative Example 1, andComparative Example 2 of the 10th cycle and the retention rate of thedischarge capacity after 10 charge and discharge cycles are recorded inTable 3 below. FIG. 4 shows a diagram illustrating the relationshipbetween the number of charge and discharge cycles and discharge capacityof the lithium battery of each of Example 1, Comparative Example 1, andComparative Example 2 of the invention at high temperature.

TABLE 3 Discharge capacity of 10th cycle Retention rate (mAh/g) (%)Example 1 172.3 98.9 Comparative 166.0 96.1 Example 1 Comparative 172.997.2 Example 2

It can be known from Table 3 and FIG. 4 that, in comparison to thelithium batteries of Comparative Example 1 and Comparative Example 2,after 10 charge and discharge cycles in a high-temperature environment,the lithium battery of Example 1 has higher capacitance retention rate,and after 10 charge and discharge cycles in a high-temperatureenvironment, the lithium battery of Example 1 still has good dischargecapacity. The results indicate that by preparing the cathode using theoligomer-polymer of the invention obtained by the polymerizationreaction of the compound containing an ethylenically unsaturated groupand the nucleophile compound including the compound shown in formula 1,the cathode can still have good structural stability in ahigh-temperature environment, such that the lithium battery can havegood capacitance, battery efficiency, and charge and discharge cyclelife. Moreover, the results also prove that the oligomer-polymer of theinvention can indeed be accepted by the current lithium battery andimprove the safety of the battery.

Although the invention has been described with reference to the aboveembodiments, it will be apparent to one of ordinary skill in the artthat modifications to the described embodiments may be made withoutdeparting from the spirit of the invention. Accordingly, the scope ofthe invention is defined by the attached claims not by the abovedetailed descriptions.

What is claimed is:
 1. An oligomer-polymer obtained by a polymerizationreaction of a compound containing an ethylenically unsaturated group anda nucleophile compound, wherein the nucleophile compound comprises acompound shown in formula 1:


2. The oligomer-polymer of claim 1, wherein a mole ratio of the compoundcontaining an ethylenically unsaturated group and the nucleophilecompound is between 2:1 and 1:1.
 3. The oligomer-polymer of claim 1,wherein the compound containing an ethylenically unsaturated groupcomprises a maleimide-based compound.
 4. The oligomer-polymer of claim3, wherein the maleimide-based compound comprises monomaleimide orbismaleimide.
 5. The oligomer-polymer of claim 1, wherein thenucleophile compound further comprises a compound shown in formula 2below:


6. The oligomer-polymer of claim 5, wherein in the nucleophile compound,a mole ratio of the compound shown in formula 1 and the compound shownin formula 2 is between 2:1 and 1:1.
 7. The oligomer-polymer of claim 1,wherein a reaction temperature of the polymerization reaction is between25° C. and 200° C.